Family Study of Congenital Hydrocephalus

Abstract

Patients (74) with uncomplicated congenital hydrocephalus who were born in Northern Ireland, UK, during 1974-1977, are considered. Three of their 159 sibs (1.89%) were also themselves hydrocephalic, which represents a recurrence risk of 26 times the population incidence. There was a smaller but significant increase of congenital hydrocephalus among 1st-cousins; 3 of 846 (0.35%) 1st-cousins were affected, 5 times the population frequency. The occurrence of neural-tube defects among sibs and cousins was similar to that for the general population. For the purpose of genetic counselling, once X-linked inheritance was excluded in uncomplicated congenital hydrocephalus, the over-all empirical risk of recurrence is approximately 1 in 50; or 1 in 40 after an affected male and 1 in 80 after a female index patient.